Vessel sealer and divider  with knife lockout

ABSTRACT

An endoscopic forceps includes a housing having a shaft attached thereto that supports a pair of jaws disposed at a distal end thereof. A drive assembly having a drive shaft with a proximal end is operable to move the jaws relative to one another from an open to closed positions. A knife assembly is operable to advance a knife through tissue disposed between the jaws and includes a flange disposed thereon. A knife lockout is included that has a flange configured to engage the proximal end of the drive shaft and a lockout arm configured to engage the flange of the knife assembly to prevent movement thereof. Movement of the jaws to the closed position causes the proximal end of the drive shaft to engage the flange on the lockout which causes the lockout arm to disengage the flange on the knife assembly to permit advancement of the knife.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/550,322, filed on Jul. 16, 2012, which is a continuation of U.S.patent application Ser. No. 12/548,566, filed on Aug. 27, 2009, theentire contents of each of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to an electrosurgical forceps and, moreparticularly, the present disclosure relates to an elongated endoscopiccombination electrosurgical forceps for sealing and/or cutting tissue.

TECHNICAL FIELD

Electrosurgical forceps utilize both mechanical clamping action andelectrical energy to effect hemostasis by heating tissue and bloodvessels to coagulate, cauterize and/or seal tissue. As an alternative toopen forceps for use with open surgical procedures, many modern surgeonsuse endoscopes and endoscopic instruments for remotely accessing organsthrough smaller, puncture-like incisions. As a direct result thereof,patients tend to benefit from less scarring and reduced healing time. Asused herein the term, endoscopic is meant to include laparoscopic.

Endoscopic instruments are inserted into the patient through a cannula,or port, which has been made with a trocar. Typical sizes for cannulasrange from three millimeters to twelve millimeters. Smaller cannulas areusually preferred, which, as can be appreciated, ultimately presents adesign challenge to instrument manufacturers who must find ways to makeendoscopic instruments that fit through the smaller cannulas.

Many endoscopic surgical procedures require cutting or ligating bloodvessels or vascular tissue. Due to the inherent spatial considerationsof the surgical cavity, surgeons often have difficulty suturing vesselsor performing other traditional methods of controlling bleeding, e.g.,clamping and/or tying-off transected blood vessels. By utilizing anendoscopic electrosurgical forceps, a surgeon can either cauterize,coagulate/desiccate and/or simply reduce or slow bleeding simply bycontrolling the intensity, frequency and duration of the electrosurgicalenergy applied through the jaw members to the tissue. Most small bloodvessels, e.g., in the range below two millimeters in diameter, can oftenbe closed using standard electrosurgical instruments and techniques.However, if a larger vessel is ligated, it may be necessary for thesurgeon to convert the endoscopic procedure into an open-surgicalprocedure and thereby abandon the benefits of endoscopic surgery.Alternatively, the surgeon can seal the larger vessel or tissue.

It is thought that the process of coagulating vessels is fundamentallydifferent than electrosurgical vessel sealing. For the purposes herein,“coagulation” is defined as a process of desiccating tissue wherein thetissue cells are ruptured and dried. “Vessel sealing” or “tissuesealing” is defined as the process of liquefying the collagen in thetissue so that it reforms into a fused mass. Coagulation of smallvessels is sufficient to permanently close them, while larger vesselsneed to be sealed to assure permanent closure.

In order to effectively seal larger vessels (or tissue) two predominantmechanical parameters should be accurately controlled—the pressureapplied to the vessel (tissue) and the gap distance between theelectrodes or tissue sealing surfaces—both of which are affected by thethickness of the sealed vessel. More particularly, accurate applicationof pressure is important to oppose the walls of the vessel; to reducethe tissue impedance to a low enough value that allows enoughelectrosurgical energy through the tissue; to overcome the forces ofexpansion during tissue heating; and to contribute to the end tissuethickness, which is an indication of a good seal. It has been determinedthat a typical jaw gap for fusing vessel walls is optimum between 0.001and 0.006 inches. Below this range, the seal may shred or tear and abovethis range the lumens may not be properly or effectively sealed.

With respect to smaller vessels, the pressure applied to the tissuetends to become less relevant whereas the gap distance between theelectrically conductive surfaces becomes more significant for effectivesealing. In other words, the chances of the two electrically conductivesurfaces touching during activation increases as vessels become smaller.

It has been found that the pressure range for assuring a consistent andeffective seal is between about 3 kg/cm2 to about 16 kg/cm2 and,preferably, within a working range of 7 kg/cm2 to 13 kg/cm2.Manufacturing an instrument that is capable of providing a closurepressure within this working range has been shown to be effective forsealing arteries, tissues and other vascular bundles.

In certain surgical operations, a bipolar forceps is used in combinationwith a monopolar forceps or monopolar coagulator to treat tissue andcontrol bleeding during the surgery. As such and during the course of aparticular operation, a surgeon may be required to substitute amonopolar instrument for the bipolar instrument, which would typicallyinvolve substitution through the trocar or cannula. As can beappreciated this may occur on more than one occasion over the course ofthe operation, which can be quite time consuming and which mayunnecessarily subject the instruments to possible non-sterileenvironments.

Certain surgical instruments have been designed that impede theadvancement of the knife or cutting member when the handles are disposedin a closed position to avoid unintended actuation or deployment of theknife through tissue. One such knife lockout design is described incommonly-owned U.S. patent application Ser. No. 11/540,335 entitledIN-LINE VESSEL SEALER AND DIVIDER filed by Dumbauld et al., then entirecontents of which is incorporated by reference herein.

SUMMARY

The present disclosure relates to an endoscopic forceps including ahousing having a shaft attached thereto which supports a pair of jawmembers disposed at a distal end thereof. A drive assembly is includedand is disposed in the housing and is operable to move the jaw membersrelative to one another from an open position wherein the jaw membersare disposed in spaced relation relative to one another to a closedposition wherein the jaw members cooperate to grasp tissue therebetween.The drive assembly includes a drive shaft having a proximal end. A knifeassembly is included and is operable to advance a knife through tissuedisposed between the jaw members. The knife assembly includes at leastone mechanical interface disposed thereon. A knife lockout is alsoincluded having a first mechanical interface configured to operablyengage the proximal end of the drive shaft and a second mechanicalinterface configured to operably engage the mechanical interface of theknife assembly to prevent movement thereof. Movement of the jaw membersto the closed position causes the proximal end of the drive shaft toengage the first mechanical interface which, in turn, causes the secondmechanical interface to disengage the mechanical interface on the knifeassembly to permit selective advancement of the knife. For example,engagement of the first mechanical interface with the proximal end ofthe drive shaft may cause rotation of the second mechanical interfaceout of engagement with the mechanical interface of the knife assemblyallowing selective actuation of the knife.

In one embodiment, a pair of handles is operatively connected to thedrive assembly; the handles are movable relative to the housing toactuate the drive assembly to move the jaw members. In anotherembodiment, the knife assembly includes a knife shaft that seats withina cap of an elongated knife sleeve supported at a proximal end of thehousing. The cap may include a flange that extends therefrom thatinterfaces with the second mechanical interface of the knife lockout.

In yet another embodiment, the knife lockout may include an adjustmentmechanism that precisely aligns the first mechanical interface of theknife lockout with the disposition of proximal end of the drive shaftwhen the jaw members are in the closed position. The adjustmentmechanism may include an eccentric nut that is manually adjustable toalign the knife lockout after assembly.

The knife lockout may also include a spring to bias the secondmechanical interface of the knife lockout in an engaged position withthe mechanical interface of the knife assembly.

The present disclosure also relates to a method of manufacturing adevice for dividing vessels or tissue and includes the initial step of:providing a forceps having a housing including a shaft attached theretothat supports a pair of jaw members and at a distal end thereof. A driveassembly is disposed in the housing and is operable to move the jawmembers relative to one another from an open position wherein the jawmembers and are disposed in spaced relation relative to one another to aclosed position wherein the jaw members and cooperate to grasp tissuetherebetween. The drive assembly includes a drive shaft having aproximal end. A knife assembly is included and is operable to advance aknife through tissue disposed between the jaw members and. The knifeassembly includes a mechanical interface disposed thereon. A knifelockout is included that has a first mechanical interface configured tooperably engage the proximal end of the drive shaft and a secondmechanical interface configured to operably engage the mechanicalinterface of the knife assembly and prevent movement thereof.

The method also includes the step of actuating the drive assembly tomove the jaw members to the closed position causing the proximal end ofthe drive shaft to engage the first mechanical interface which, in turn,causes the second mechanical interface to disengage the mechanicalinterface on the knife assembly and permit selective advancement of theknife.

Another method according to the present disclosure includes a method forseparating tissue which includes the steps of: positioning a knifelockout to prevent translation of a knife blade through a knife channeldefined between a pair of jaw members; actuating a drive assembly toclose the pair of jaw members about tissue and position a proximal endof a drive shaft of the drive assembly to a proximal-most position; andengaging a first mechanical interface extending from the knife lockoutwith the proximal end of the drive shaft to reposition a secondmechanical interface of the knife lockout to allow translation of theknife blade.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1A is a top, perspective view of an endoscopic forceps shown in anopen configuration and including a housing, a handle assembly, a shaftand an end effector assembly according to an embodiment of the presentdisclosure;

FIG. 1B is a top, perspective view of the endoscopic forceps of FIG. 1Ashowing the end effector assembly in a closed configuration anembodiment of the present disclosure;

FIG. 2A is an enlarged, top view of the forceps of FIG. 1A showing thedisposition of the internal components when the forceps is in an openconfiguration;

FIG. 2B is an enlarged, top view of the forceps of FIG. 1B showing thedisposition of the internal components when the forceps is in a closedconfiguration;

FIG. 3A is an enlarged, top view showing the knife actuator afteractuation;

FIG. 3B is a greatly-enlarged, side cross sectional view of the endeffector assembly showing the position of the knife after actuation;

FIG. 4A is a greatly-enlarged, perspective view of the bottom jaw of theend effector assembly with parts separated;

FIG. 4B is a greatly-enlarged, perspective view of the top jaw of theend effector assembly with parts separated;

FIG. 5 is a greatly-enlarged, perspective view of the elongated shaftfor housing various moving parts of the drive assembly and knifeassembly;

FIG. 6 is an internal view of an alternate embodiment of a forcepsaccording to the present disclosure showing a knife lockout disposed inan engaged position;

FIG. 7 is an internal view of the embodiment of FIG. 6 showing the knifelockout disposed in a disengaged position by virtue of the movement ofthe drive shaft; and

FIG. 8 is an enlarged, exploded view of the knife lockout of FIG. 6.

DETAILED DESCRIPTION

During certain tissue treatment procedures that require transaction oftissue, it may prove useful to employ a knife lockout to preventunintended advancement of the knife or cutting mechanism through thetissue before the tissue is treated. Moreover, in some instances it mayprove useful to prevent translation of the knife when the jaw membersare not fully clamped about tissue or are incorrectly clamped abouttissue (e.g., too much tissue between jaw members). In this instance,preventing translation of the knife or cutting mechanism will preventthe knife from jamming, miscuing, buckling, pinching or de-railing upontranslation or retraction of the knife blade. In some instances,improper deployment or retraction of the knife may render the forcepsunusable.

Turning now to FIGS. 1A and 1B, one embodiment of an endoscopicelectrosurgical forceps 10 is shown for use with various surgicalprocedures and generally includes a housing 20, a handle assembly 30, arotating assembly 80, a knife assembly 70 and an end effector assembly100 which mutually cooperate to grasp, seal and divide tubular vesselsand vascular tissue. Although the majority of the figure drawings depicta forceps 10 for use in connection with endoscopic surgical procedures,the present disclosure may be used for more traditional open surgicalprocedures.

Forceps 10 includes a shaft 12 which has a distal end 16 dimensioned tomechanically engage the end effector assembly 100 and a proximal end 14which mechanically engages the housing 20. Details of how the shaft 12connects to the end effector assembly 100 are described in more detailbelow. The proximal end 14 of shaft 12 is received within the housing 20and the connections relating thereto are also described in detail below.In the drawings and in the descriptions which follow, the term“proximal”, as is traditional, will refer to the end of the forceps 10which is closer to the user, while the term “distal” will refer to theend which is further from the user.

Forceps 10 also includes an electrosurgical cable 310 that connects theforceps 10 to a source of electrosurgical energy, e.g., a generator (notshown). Generators such as those sold by Covidien, located in BoulderColo. may be used as a source of both bipolar electrosurgical energy forsealing vessel and vascular tissues as well as monopolar electrosurgicalenergy which is typically employed to coagulate or cauterize tissue. Itis envisioned that the generator may include various safety andperformance features including isolated output, impedance control and/orindependent activation of accessories.

Handle assembly 30 includes two movable handles 30 a and 30 b disposedon opposite sides of housing 20. Handles 30 a and 30 b are movablerelative to one another to actuate the end effector assembly 100 asexplained in more detail below with respect to the operation of theforceps 10.

Rotating assembly 80 is mechanically coupled to housing 20 and isrotatable approximately 90 degrees in either direction about alongitudinal axis “A.” Rotating assembly 80, when rotated, rotates shaft12, which, in turn, rotates end effector assembly 100. Such aconfiguration allows end effector assembly 100 to be rotatedapproximately 90 degrees in either direction with respect to housing 20.

As mentioned above, end effector assembly 100 is attached at the distalend 16 of shaft 12 and includes a pair of opposing jaw members 110 and120 (see FIGS. 4A and 4B). Handles 30 a and 30 b of handle assembly 30ultimately connect to drive assembly 60 (see FIG. 2A) which, together,mechanically cooperate to impart movement of the jaw members 110 and 120from a first, open position wherein the jaw members 110 and 120 aredisposed in spaced relation relative to one another, to a second,clamping or closed position wherein the jaw members 110 and 120cooperate to grasp tissue therebetween.

Turning now to the more detailed features of the present disclosure asdescribed with respect to FIGS. 1A-5, handles 30 a and 30 b each includean aperture 33 a and 33 b, respectively, defined therein which enables auser to grasp and move each respective handle 30 a and 30 b relative toone another. Handles 30 a and 30 b also include ergonomically-enhancedgripping elements 39 a and 39 b, respectively, disposed along an outeredge thereof which are designed to facilitate gripping of the handles 30a and 30 b during activation. It is envisioned that gripping elements 39a and 39 b may include one or more protuberances, scallops and/or ribsto enhance gripping.

As best illustrated in FIG. 1A, handles 30 a and 30 b are configured toextend outwardly on opposite sides from a transverse axis “B” definedthrough housing 20 which is perpendicular to longitudinal axis “A”.Handles 30 a and 30 b are movable relative to one another in a directionparallel to axis “B” to open and close the jaw members 110 and 120 asneeded during surgery. Details relating to the inner-working componentsof forces 10 are disclosed in commonly-owned U.S. patent applicationSer. No. 11/540,335, the entire contents of which being incorporated byreference herein. This forceps style is commonly referred to as an“in-line” or hemostat style forceps. In-line hemostats or forceps aremore commonly manufactured for open surgical procedures and typicallyinclude a pair of shafts having integrally coupled handles which aremovable relative to one another to open and close the jaw membersdisposed at the distal end thereof.

As best seen in FIGS. 2A and 2B, the distal end of each handle 30 a and30 b is selectively moveable about pivot pins 34 a and 34 b attached toa distal end 21 of the housing 20 to actuate the jaw members 110 and120. Movement of the handles 30 a and 30 b away from one another (andthe housing 20) unlocks and opens the handles 30 a and 30 b and, inturn, the jaw members 110 and 120 for subsequent grasping or re-graspingof tissue. In one embodiment, the handles 30 a and 30 b may be biased inan open configuration to facilitate handling and manipulation of the jawmembers 110 and 120 within an operative field. Various spring-likemechanisms are contemplated which may be utilized to accomplish thispurpose.

Movable handles 30 a and 30 b are designed to provide a distinctlever-like mechanical advantage over conventional handle assemblies. Theenhanced mechanical advantage for actuating the jaw members 110 and 120is gained by virtue of the unique position and combination of severalinter-cooperating elements which reduce the overall user forcesnecessary to obtain and maintain the jaw members 110 and 120 under idealoperating pressures of about 3 kg/cm2 to about 16 kg/cm2. Detailsrelating to the working components the handle assembly and driveassembly are disclosed in above-mentioned U.S. patent application Ser.No. 11/540,335. In other words, it is envisioned that the combination ofthese elements and their positions relative to one another enables theuser to gain lever-like mechanical advantage to actuate the jaw members110 and 120 enabling the user to close the jaw members 110 and 120 withlesser force while still generating the required forces necessary toeffect a proper and effective tissue seal.

As shown in FIGS. 4A, 4B, and 5, the end effector assembly 100 isdesigned as a bilateral assembly, i.e., both jaw members 110 and 120pivot relative to one another about a pivot pin 185 disposedtherethrough. Each jaw member 110 and 120 includes a correspondingflange 113 and 123 that pivots about a pivot pin 185 disposed betweenthe jaw members 110 and 120 upon translation of a drive rod 180 asexplained in more detail below.

More particularly, jaw members 110 and 120 include proximal flanges 113and 123, respectively, which each include an elongated angled slot 181 aand 181 b, respectively, defined therethrough. Drive pin 180 mounts jawmembers 110 and 120 to the end of a rotating shaft 18 and within acavity 17′ defined at the distal ends 17 a and 17 b of drive actuator orsleeve 17 (See FIG. 5).

More particularly, upon actuation of the drive assembly 60, the drivesleeve 17 reciprocates which, in turn, causes the drive pin 180 to ridewithin slots 181 a and 181 b to open and close the jaw members 110 and120 as desired. The jaw members 110 and 120, in turn, pivot about pivotpin 185 disposed through respective pivot holes 186 a and 186 b definedwithin flanges 113 and 123 of the jaw members 110 and 120. As can beappreciated, squeezing handles 30 a and 30 b toward the housing 20 pullsdrive sleeve 17 and drive pin 180 proximally to close the jaw members110 and 120 about tissue grasped therebetween and pushing the sleeve 17distally opens the jaw members 110 and 120 for grasping purposes.

Flanges 113 and 123 of jaw members 110 and 120, respectively, arepositioned in an abutting relationship with one another. Flanges 113,123 are assembled and engaged via pivot pin 185 disposed throughapertures 186 a, and 186 b, respectively. Further, flanges 113 and 123are pivotable about one another via drive pin 180 disposed through slots181 a and 181 b and of flanges 113 and 123, respectively. A knife pathmay be defined between flanges 113 and 123 that longitudinally alignswith knife channels 115 a and 115 b defined within jaw members 110 and120, such that knife blade 190 travels in a substantially straight paththrough knife channels 115 a and 115 b defined in jaw members 110 and120, respectively.

As shown in FIG. 4B, jaw member 110 also includes a support base 119which extends distally from flange 113 and which is configured tosupport an insulative plate 119′ thereon. Insulative plate 119′, inturn, is configured to support an electrically conductive tissueengaging surface or sealing plate 112 thereon. Sealing plate 112 may beaffixed atop the insulative plate 119′ and support base 119 in any knownmanner in the art, snap-fit, over-molding, stamping, ultrasonicallywelded, etc. Support base 119 together with the insulative plate 119′and electrically conductive tissue engaging surface 112 are encapsulatedby an outer insulative housing 114. Outer housing 114 includes a cavity114 a that is dimensioned to securely engage the electrically conductivesealing surface 112 as well as the support base 119 and insulative plate119′. This may be accomplished by stamping, by overmolding, byovermolding a stamped electrically conductive sealing plate and/or byovermolding a metal injection molded seal plate. All of thesemanufacturing techniques produce jaw member 110 having an electricallyconductive surface 112 which is substantially surrounded by aninsulating substrate 114.

The electrically conductive surface or sealing plate 112 and the outerhousing 114, when assembled, form longitudinally-oriented knife channel115 a defined therethrough for reciprocation of the knife blade 190. Itis envisioned that the knife channel 115 a cooperates with correspondingknife channel 115 b defined in jaw member 120 to facilitate longitudinalextension of the knife blade 190 along a preferred cutting plane toeffectively and accurately separate the tissue along the formed tissueseal. As discussed above, when knife blade 190 is deployed, at least aportion of knife blade 190 advances into knife channels 115 a and 115 b.Handle 30 a may include a lockout flange (not shown) which preventsactuation of the knife assembly 70 when the handle 30 a is open thuspreventing accidental or premature activation of the knife blade 190through the tissue. A more detailed discussion of the lockout flange isdiscussed in above-mentioned U.S. patent application Ser. No.11/540,335.

As explained above and as illustrated in FIGS. 4A and 4B, the knifechannel 115 is formed when the jaw members 110 and 120 are closed. Inother words, the knife channel 115 includes two knife channelhalves—knife channel half 115 a disposed in sealing plate 112 of jawmember 110 and knife channel half 115 b disposed sealing plate 122 ofjaw member 120. Knife channel 115 may be configured as a straight slotwith no degree of curvature which, in turn, causes the blade 190 to movethrough the tissue in a substantially straight fashion. Alternativelyand as shown, the knife channel 115 may be curved which has certainsurgical advantages.

As mentioned above, when the jaw members 110 and 120 are closed abouttissue, knife channels 115 a and 115 b form a complete knife channel 115to allow longitudinal extension of the knife blade 190, from the knifepath, in a distal fashion to sever tissue along a tissue seal. Knifechannel 115 may be completely disposed in one of the two jaw members,e.g., jaw member 120, depending upon a particular purpose. It is alsoenvisioned that jaw member 120 may be assembled in a similar manner asdescribed above with respect to jaw member 110.

FIGS. 6-8 show another embodiment of a knife lockout 1200 for use withforceps 10. Unlike the described knife lockout element of commonly-ownedU.S. patent application Ser. No. 11/540,335 that prevents advancement ofthe knife blade 190 when the handles 30 a and 30 b of forceps 10 aredisposed in an open position, lockout 1200 prevents advancement of theknife blade 190 when the jaw members 110 and 120 are disposed in an openposition. More particularly, the knife lockout 1200 operablycommunicates with the drive shaft 1017 such that the position of thedrive shaft 1017 (which regulates the opening and closing of the jawmembers 110 and 120) dictates a user option for selective advancement ofthe knife assembly 70. In other words, the disposition of knife lockout1200 (e.g., “engaged” or “disengaged”) is dependent on the position ofthe drive shaft 1017 and not necessarily the position of the handles1030 a and 1030 b. As explained below, the manufacturer can preciselyorient an eccentric nut 1225 of the lockout 1200 such that the knifeshaft 1071 (and therefore knife blade 190) can only be advanced when theproximal end 1017′ of the drive shaft 1017 is fully retracted and thejaw members 110 and 120 are fully closed about tissue.

More particularly, and with respect to FIG. 6, forceps 1000 is similarto the above described forceps 10 with only those exceptions beingdiscussed hereinbelow. Forceps 1000 includes movable handles 1030 a and1030 b which together cooperate to actuate the drive assembly (not shownin this embodiment) as discussed above with respect to FIGS. 2A and 2B.In this envisioned embodiment, a proximal end 1017′ of the drive shaft1017 is configured to extend proximally relative to the drive assemblyto permit engagement with the knife lockout 1200 (as explained in detailbelow) when the jaw members 110 and 120 are fully closed about tissue.

As shown in FIGS. 6 and 8, the knife assembly 70 is configured to extendproximally and settle within a proximal end of the housing 1020. Theknife shaft 1071 includes a T-shaped proximal end 1075 that seats withina cap 1110 of an elongated knife support sleeve 1115 having a flange1110 that extends therefrom. Details relating to the interaction of thecap 1100 and the knife lockout 1200 are explained below.

As shown in FIG. 8, knife lockout 1200 includes a lever 1210 that isconfigured to be supported within the housing 1020 and includes alockout base 1213 having a lockout arm 1214, a spring arm 1216 and aflange 1212 that extend outwardly therefrom. Flange 1212 is configuredto operably engage the proximal end 1017′ of drive shaft 1017 when thejaw members 110 and 120 are moved to a fully closed position (See FIG.7). Upon contact, the flange 1212 is rotated proximally which, in turn,rotates the lockout base 1210 and lockout arm 1214 clockwise such thatthe proximal end 1214′ of the lockout arm 1214 disengages from theflange 1110 of the knife assembly cap 1100. When disengaged, the knifeassembly 70 is selectively actuatable by the user to sever tissuedisposed between the jaw members 110 and 120. The knife assembly 70 maybe spring-biased to return to a fully retracted position upon releasethereof.

It is important to note that the knife lockout 1200 is also springbiased such that when the jaw members 110 and 120 are moved from theirfully closed position and the proximal end 1017′ of the drive shaft 1017no longer engages the flange 1212, the spring arm 1216 forces thelockout arm 1214 counter-clockwise to reengage the flange 1110 of theknife assembly 70 thereby preventing movement thereof. The spring arm1216 is biased against the inner periphery of the housing 1020. As canbe appreciated, this feature insures that the disposition of the jawmembers 110 and 120 and not the disposition of the handles 1030 a and1030 b dictates whether the knife assembly 70 may be actuated toseparate tissue. In other words, the jaw members must be fully closed inorder for the knife 190 to become available for tissue separation.

An adjustment mechanism, e.g., an eccentric adjustment nut 1225, isconfigured to allow precise alignment of the knife lockout 1200 with thefully retracted position of the proximal end 1017′ of the drive shaft1017. This allows a manufacturer to precisely adjust the relativeposition of the flange 1212 of the knife lockout 1200 with respect tothe position of the proximal end 1017′ of the drive shaft 1017 afterassembly of the internal components of the forceps 1000 to assure properdisengagement of the knife lockout 1200 when the jaw members 110 and 120are fully closed. The eccentric adjustment nut 1225 includes a pair ofopposing slits 1227 that are configured to facilitate rotation of thenut 1225 which, in turn, precisely aligns the lockout 1200. Theeccentric nut 1225 is configured to seat within an aperture defined withthe lockout base 1213. A locking bolt 1220 is utilized to lock the nut1225 in place after alignment of the lockout 1200. Once the housing 1020is fully assembled, the eccentric adjustment nut 1225 and locking bolt1220 are secured into place. The locking bolt 1220 may be integrallyassociated with the housing 20 or may be eliminated and replaced with analternative boss (not shown).

Other types of alignment mechanisms are also contemplated and include: aliving hinge and set screw combination that may be configured to varythe angle of pivot of the lockout 1200; a diagonal slot arrangement thatallows precise alignment of the lockout 1200 which is then locked by aset screw; a gear and ratchet alignment device which can be preciselyaligned and then locked; a crush feature that locks the lockout device1200 in an aligned configuration; one or more shims that lock thelockout in precise configuration after alignment; and/or a flexible postand set screw arrangement that aligns and locks the lockout device 1200.

It is contemplated that the above described forceps 100 may beconfigured in combination with any of the aforementioned features of theforceps 10 described with respect to FIG. 1A-5 or with respect to any ofthe features described in above-mentioned and commonly-owned U.S. patentapplication Ser. No. 11/540,335. For example, the forceps 1000 mayinclude a safety lockout, e.g., lockout that prevents activation of oneor both switches depending upon the disposition of the jaw members 110and 120.

A monopolar lockout may also be included that prevents activation of themonopolar switch when the jaw members 110 and 120 are disposed in theopen position. The monopolar lockout may include a mechanical interfacedisposed on one or both of the handles 1030 a, 1030 b that preventsactivation of the monopolar switch when the handles 1030 a, 1030 b aredisposed in an open or first position relative to the housing 1020 andpermits activation of the monopolar switch when the handles 1030 a, 1030b are disposed in a closed or second position relative to the housing1020. For example, a pressure activated safety switch (not shown) may bedisposed in the housing 1020 and movement of the handles 1030 a, 1030 bfrom the open position to the closed position and/or movement of the jawmembers from the open to closed position relative to the housing 1020closes the pressure activated safety switch to allow activation of themonopolar switch.

In another example, the monopolar lockout may include a mechanicalinterface disposed on one (or both) of the handles 1030 a and 1030 bthat prevents activation of the monopolar switch (or bipolar switch orboth switches) when the handles 1030 a and 1030 b are disposed in afirst position relative to the housing 1020 and permits activation ofone or both switch when the handles 1030 a and 1030 b are disposed in asecond position relative to the housing.

The present disclosure also relates to a method of manufacturing adevice for dividing tissue including the initial step of providing aforceps 1000 having a housing 1020 including a shaft 12 attached theretothat supports a pair of jaw members 110 and 120 at a distal end thereof.A drive assembly 60 is disposed in the housing 1020 and is operable tomove the jaw members 110 and 120 relative to one another from an openposition wherein the jaw members 110 and 120 are disposed in spacedrelation relative to one another to a closed position wherein the jawmembers 110 and 120 cooperate to grasp tissue therebetween. The driveassembly 60 includes a drive shaft 1017 having a proximal end 1017′. Aknife assembly 70 is included and is operable to advance a knife 190through tissue disposed between the jaw members 110 and 120. The knifeassembly 70 includes a mechanical interface, e.g., flange 1110, disposedthereon. A knife lockout 1200 is included that has a first mechanicalinterface, e.g., flange 1212, configured to operably engage the proximalend 1017′ of the drive shaft 1017 and a second mechanical interface,e.g., lockout arm 1214, configured to operably engage the mechanicalinterface 1110 of the knife assembly 70 and prevent movement thereof.

The method also includes the step of actuating the drive assembly 60 tomove the jaw members 110 and 120 to the closed position causing theproximal end 1017′ of the drive shaft 1017 to engage the firstmechanical interface 1212 which, in turn, causes the second mechanicalinterface 1214 to disengage the mechanical interface 1110 on the knifeassembly 70 and permit selective advancement of the knife 190.

Another method according to the present disclosure includes a method forseparating tissue which includes the steps of: positioning a knifelockout 1200 to prevent translation of a knife blade 190 through a knifechannel 115 defined between a pair of jaw members 110 and 120; actuatinga drive assembly 60 to close the pair of jaw members 110 and 120 abouttissue and position a proximal end 1017′ of a drive shaft 1017 of thedrive assembly 60 to a proximal-most position; and engaging a firstmechanical interface 1212 extending from the knife lockout 1200 with theproximal end 1017′ of the drive shaft 1017 to reposition a secondmechanical interface 1214 of the knife lockout 1200 to allow translationof the knife blade 190.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. For example, it may be preferable to add other features tothe forceps 10, 1000, e.g., an articulating assembly to axially displacethe end effector assembly 100 relative to the elongated shaft 12. Whileseveral embodiments of the disclosure have been shown in the drawings,it is not intended that the disclosure be limited thereto, as it isintended that the disclosure be as broad in scope as the art will allowand that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

What is claimed is:
 1. An endoscopic forceps, comprising: a housinghaving a shaft attached thereto, the shaft including a pair of jawmembers disposed at a distal end thereof; a drive assembly operable tomove the jaw members relative to one another from an open positionwherein the jaw members are disposed in spaced relation relative to oneanother to a closed position wherein the jaw members cooperate to grasptissue therebetween, the drive assembly including a drive shaft having aproximal end; a knife assembly operable to advance a knife throughtissue disposed between the jaw members; and a knife lockout including afirst mechanical interface configured to operably engage the proximalend of the drive shaft and a second mechanical interface configured tooperably engage the knife assembly and prevent movement thereof, whereinmovement of the jaw members to the closed position causes the secondmechanical interface to disengage the knife assembly.
 2. An endoscopicforceps according to claim 1, further comprising a pair of handlesoperatively connected to the drive assembly and movable relative to thehousing to actuate the drive assembly to move the jaw members.
 3. Anendoscopic forceps according to claim 1, wherein the knife assemblyincludes a knife shaft that seats within a cap of an elongated knifesleeve supported at a proximal end of the housing, the cap including aflange that extends therefrom that interfaces with the second mechanicalinterface of the knife lockout.
 4. An endoscopic forceps according toclaim 1, wherein engagement of said first mechanical interface with theproximal end of the drive shaft causes rotation of the second mechanicalinterface out of engagement with the knife assembly.
 5. An endoscopicforceps according to claim 1, wherein the knife lockout includes aspring operable to bias the second mechanical interface of the knifelockout in an engaged position with the knife assembly.
 6. An endoscopicforceps according to claim 1, wherein at least one jaw member is adaptedto connect to an electrosurgical energy source for providingelectrosurgical energy to tissue disposed between the jaw members.
 7. Amethod of dividing tissue, comprising the steps of: providing a forcepshaving: a housing including a shaft attached thereto, the shaft having apair of jaw members disposed at a distal end thereof; a drive assemblyoperable to move the jaw members relative to one another from an openposition wherein the jaw members are disposed in spaced relationrelative to one another to a closed position wherein the jaw memberscooperate to grasp tissue therebetween, the drive assembly including adrive shaft having a proximal end; a knife assembly operable to advancea knife through tissue disposed between the jaw members; and a knifelockout including a first mechanical interface configured to operablyengage the proximal end of the drive shaft and a second mechanicalinterface configured to operably engage the knife assembly and preventmovement thereof; and actuating the drive assembly to move the jawmembers to the closed position causing the second mechanical interfaceto disengage the knife assembly.
 8. A method according to claim 7,further comprising the step of biasing the knife lockout to preventtranslation of the knife.
 9. A method of separating tissue, comprisingthe steps of: positioning a knife lockout to prevent translation of aknife through a knife channel defined between a pair of jaw members;actuating a drive assembly to close the pair of jaw members about tissueand position a proximal end of a drive shaft of the drive assembly to aproximal-most position; and engaging the knife lockout with the proximalend of the drive shaft to reposition the knife lockout to allowtranslation of the knife.
 10. A method according to claim 9, furthercomprising the step of biasing the knife lockout to prevent translationof the knife.